Parasitics capacitances act more and more in timing. They are linked
but it's a dead lock. To compute timing, you have to know the exact
capacitance to use and to know the cross-talking signals, you have to
know when they are switching.

My approche is to use a relaxation loop modifying the capacitance each
time after the time computation until the system "stabilises". Problem
is that the system can not in some case be stable.